Folic Acid Rescues Dopaminergic Neurons in MPTP-Induced Mice by Inhibiting the NLRP3 Inflammasome and Ameliorating Mitochondrial Impairment.

Parkinson's disease (PD) is marked by the degeneration of dopaminergic neurons of the substantia nigra (SN), with neuroinflammation and mitochondrial dysfunction being key contributors. The neuroprotective potential of folic acid (FA) in the dopaminergic system of PD was assessed in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model. MPTP (20 mg/kg of body weight) was administered to C57BL/6J mice to simulate PD symptoms followed by FA treatment (5 mg/kg of body weight). Behavioral tests, pole, rotarod, and open-field tests, evaluated motor function, while immunohistochemistry, ELISA, RT-qPCR, and Western blotting quantified neuroinflammation, oxidative stress markers, and mitochondrial function. FA supplementation considerably improved motor performance, reduced homocysteine levels and mitigated oxidative damage in the SN. The FA-attenuated activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome lessened glial cell activity and reduced neuroinflammation. At the molecular level, FA reduced DNA damage, downregulated phosphorylated p53, and induced the expression of peroxisome proliferator-activated receptor α coactivator 1α (PGC-1α), enhancing mitochondrial function. Therefore, FA exerts neuroprotection in MPTP-induced PD by inhibiting neuroinflammation via NLRP3 inflammasome suppression and promoting mitochondrial integrity through the p53-PGC-1α pathway. Notable limitations of our study include its reliance on a single animal model and the incompletely elucidated mechanisms underlying the impact of FA on mitochondrial dynamics. Future investigations will explore the clinical utility of FA and its molecular mechanisms, further advancing it as a potential therapeutic for managing and delaying the progression of PD.

Asiaticoside exerts neuroprotection through targeting NLRP3 inflammasome activation.

BACKGROUND: Parkinson's disease (PD), a neurodegenerative disorder, is characterized by motor symptoms due to the progressive loss of dopaminergic neurons in the substantia nigra (SN) and striatum (STR), alongside neuroinflammation. Asiaticoside (AS), a primary active component with anti-inflammatory and neuroprotective properties, is derived from Centella asiatica. However, the precise mechanisms through which AS influences PD associated with inflammation are not yet fully understood. PURPOSE: This study aimed to explore the protective mechanism of AS in PD. METHODS: Targets associated with AS and PD were identified from the Swiss Target Prediction, Similarity Ensemble Approach, PharmMapper, and GeneCards database. A protein-protein interaction (PPI) network was constructed to identify potential therapeutic targets. Concurrently, GO and KEGG analyses were performed to predict potential signaling pathways. To validate these mechanisms, the effects of AS on 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD in mice were investigated. Furthermore, neuroinflammation and the activation of the NLRP3 inflammasome were assessed to confirm the anti-inflammatory properties of AS. In vitro experiments in BV2 cells were then performed to investigate the mechanisms of AS in PD. Moreover, CETSA, molecular docking, and molecular dynamics simulations (MDs) were performed for further validation. RESULTS: Network pharmacology analysis identified 17 potential targets affected by AS in PD. GO and KEGG analyses suggested the biological roles of these targets, demonstrating that AS interacts with 149 pathways in PD. Notably, the NOD-like receptor signaling pathway was identified as a key pathway mediating AS's effect on PD. In vivo studies demonstrated that AS alleviated motor dysfunction and reduced the loss of dopaminergic neurons in MPTP-induced PD mice. In vitro experiments demonstrated that AS substantially decreased IL-1ß release in BV2 cells, attributing this to the modulation of the NLRP3 signaling pathway. CETSA and molecular docking studies indicated that AS forms a stable complex with NLRP3. MDs suggested that ARG578 played an important role in the formation of the complex. CONCLUSION: In this study, we first predicted that the potential target and pathway of AS's effect on PD could be NLRP3 protein and NOD-like receptor signaling pathway by network pharmacology analysis. Further, we demonstrated that AS could alleviate symptoms of PD induced by MPTP through its interaction with the NLRP3 protein for the first time by in vivo and in vitro experiments. By binding to NLRP3, AS effectively inhibits the assembly and activation of the inflammasome. These findings suggest that AS is a promising inhibitor for PD driven by NLRP3 overactivation.

TMT-based quantitative proteomics analysis of neuroprotective effects of Forsythoside A on the MPTP-induced Parkinson's disease mouse model.

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characteristized by the presence of dyskinesia and the progressive loss of dopaminergic neurons. Although certain drugs can mitigate the symptoms of PD, they are unable to delay the disease progression, and their prolonged use may result in complications. Therefore, there exists an urgent necessity to identify potential agents that can effectively delay PD progression with fewer side effects. Recent research has unveiled that several traditional Chinese medicines (TCM) exhibit neuroprotective properties in various models pertinent to PD. Forsythoside A (FSA), the primary bioactive compound derived from TCM Lianqiao, has undergone extensive research in animal models of Alzheimer's disease and cerebral ischemia. However, the investigation into the impact of FSA on PD is limited in existing research. In this study, we aimed to evaluate the neuroprotective effects of FSA on MPTP-induced PD mouse model. FSA demonstrated significant improvements in the behavioral and neuropathological changes triggered by MPTP in mice. Furthermore, it exerted a suppressive effect on the activations of astrocyte and microglia. Meanwhile, Tandem mass tag (TMT)-based quantitative proteomics of striatal tissue and bioinformatics analysis were performed to elucidate the underlying mechanisms of FSA on PD mouse model. Proteomics demonstrated a total of 68 differentially expressed proteins (DEPs) were identified between HFSA and MPTP groups including 26 upregulated and 42 downregulated. Systematic bioinformatics analysis of the 68 DEPs illustrated that they were predominantly related to estrogen signaling pathway and calcium signaling pathway. The related DEPs (PLCß4, Grm2, HPAC and Cox4i1) expression levels were verified by Western blot. FSA effectively restored the altered expression of the four DEPs induced by MPTP. Summarily, FSA exerted remarkable neuroprotective effects in MPTP-induced mice. Further, our research may provide proteomics insights that contribute to the further exploration of FSA as a potential treatment for PD.

Feruloylated oligosaccharides ameliorate MPTP-induced neurotoxicity in mice by activating ERK/CREB/BDNF/TrkB signalling pathway.

BACKGROUND: Feruloylated oligosaccharides (FOs) are natural esterification products of ferulic acid and oligosaccharides. STUDY DESIGN: In this study, we examined whether FOs contribute to the ensured survival of nigrostriatal dopamine neurons and inhibition of neuroinflammation in Parkinson's disease (PD). METHODS: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg) was injected intraperitoneally into mice to establish a Parkinson's disease (PD) mouse model. FOs (15 and 30 mg/kg) were orally administered daily to the MPTP-treated mice. The rotarod test, balance beam test, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), quantitative PCR (qPCR), and western blot analyses were performed to examine the neuroprotective effects of FOs on MPTP-treated mice. RESULTS: Our study indicated that FOs increased the survival of dopamine neurons in the substantia nigra pars compacta (SNc) of the MPTP-treated mice. The neuroprotective effects of FOs were accompanied by inhibited glial activation and reduced inflammatory cytokine production. The mechanistic experiments revealed that the neuroprotective effects of FOs might be mediated through the activation of the ERK/CREB/BDNF/TrkB signalling pathway. CONCLUSION: This study provides new insights into the mechanism underlying the anti-neuroinflammatory effect of phytochemicals and may facilitate the development of dietary supplements for PD patients. Our results indicate that FOs can be used as potential modulators for the prevention and treatment of PD.

Hyperbaric Oxygen Therapy Improves Parkinson's Disease by Promoting Mitochondrial Biogenesis via the SIRT-1/PGC-1α Pathway.

Hyperbaric oxygen therapy (HBOT) has been suggested as a potential adjunctive therapy for Parkinson's disease (PD). PD is a neurodegenerative disease characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The aim of this study was to investigate the protective mechanisms of HBOT on neurons and motor function in a 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD and 1-methyl-4-phenylpyridinium (MPP+)-mediated neurotoxicity in SH-SY5Y cells on the potential protective capability. In vivo: male C57BL/6 mice were randomly divided into three groups: control, MPTP group and MPTP+HBOT group. The MPTP-treated mice were intraperitoneally received MPTP (20 mg/kg) four times at 2 h intervals within a day. The day after MPTP treatment, MPTP+HBOT mice were exposed to hyperbaric oxygen at 2.5 atmosphere absolute (ATA) with 100% oxygen for 1 h once daily for 7 consecutive days. In vitro: retinoic acid (RA)-differentiated SH-SY5Y cells were treated with MPP+ for 1 h followed by hyperbaric oxygen at 2.5 ATA with 100% oxygen for 1 h. The results showed that MPTP induced a significant loss in tyrosine hydroxylase (TH)-positive neurons in the SNpc of mice. HBOT treatment significantly increased the number of TH-positive neurons, with enhanced neurotrophic factor BDNF, decreased apoptotic signaling and attenuated inflammatory mediators in the midbrain of MPTP-treated mice. In addition, MPTP treatment decreased the locomotor activity and grip strength of mice, and these effects were shown to improve after HBOT treatment. Furthermore, MPTP decreased mitochondrial biogenesis signaling (SIRT-1, PGC-1α and TFAM), as well as mitochondrial marker VDAC expression, while HBOT treatment was shown to upregulate protein expression. In cell experiments, MPP+ reduced neurite length, while HBOT treatment attenuated neurite retraction. Conclusions: the effects of HBOT in MPTP-treated mice might come from promoting mitochondrial biogenesis, decreasing apoptotic signaling and attenuating inflammatory mediators in the midbrain, suggesting its potential benefits in PD treatment.

Neuroprotective effects of Tongtian oral liquid, a Traditional Chinese Medicine in the Parkinson's disease-induced zebrafish model.

Traditional Chinese medicine (TCM) is used in the treatment of Parkinson's disease (PD) worldwide. Tongtian Oral Liquid (TTKFY) is one such patented TCM, and a poly-herbal formulation, composed of 11 herbal constituents, which possess neuroprotective, antioxidant, pain-relieving properties. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP), a neurotoxicant is used to induce PD in animal models. The present study was aimed to evaluate the neuroprotective effects of TTKFY, on dopaminergic neuron development, antioxidant activities, and gene expression involved in the dopaminergic pathway in the MPTP-treated zebrafish model. Zebrafish larvae were treated with MPTP (70 µM) to induce PD and then by different concentrations (0.5, 1, 2, 4 ml/L) of TTKFY. Transgenic zebrafish Vmat: GFP at 5 dpf were used to observe the development of dopaminergic neurons. The activities of T-Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malonaldehyde (MDA) and mRNA gene expression of dopamine pathway were quantified. MPTP-treated zebrafish larvae showed degeneration of dopaminergic neurons, locomotion dysfunction, diminished activities of antioxidant enzymes, MDA accumulation, and altered gene expression of dopamine pathway. In contrast, TTKFY protected dopaminergic neurons, ameliorated behavioral impairments, antioxidant activities and mRNA gene expression of dopamine pathway in a dose-dependent manner. Thus, TTKFY confers protective effects against MPTP-induced neurotoxicity and the mechanisms of protection may be related to the recovery of dopaminergic neurons by reducing oxidative stress via restoring cellular defense mechanisms and thereby highlighting its therapeutic potential to prevent the progression of PD. Further studies are necessary to elucidate the mechanism of action of TTKFY on neuroprotection in the MPTP-induced PD model.

Chicoric Acid Prevents Neuroinflammation and Neurodegeneration in a Mouse Parkinson's Disease Model: Immune Response and Transcriptome Profile of the Spleen and Colon.

Chicoric acid (CA), a polyphenolic acid compound extracted from chicory and echinacea, possesses antiviral, antioxidative and anti-inflammatory activities. Growing evidence supports the pivotal roles of brain-spleen and brain-gut axes in neurodegenerative diseases, including Parkinson's disease (PD), and the immune response of the spleen and colon is always the active participant in the pathogenesis and development of PD. In this study, we observe that CA prevented dopaminergic neuronal lesions, motor deficits and glial activation in PD mice, along with the increment in striatal brain-derived neurotrophic factor (BDNF), dopamine (DA) and 5-hydroxyindoleacetic acid (5-HT). Furthermore, CA reversed the level of interleukin-17(IL-17), interferon-gamma (IFN-γ) and transforming growth factor-beta (TGF-ß) of PD mice, implicating its regulatory effect on the immunological response of spleen and colon. Transcriptome analysis revealed that 22 genes in the spleen (21 upregulated and 1 downregulated) and 306 genes (190 upregulated and 116 downregulated) in the colon were significantly differentially expressed in CA-pretreated mice. These genes were functionally annotated with GSEA, GO and KEGG pathway enrichment, providing the potential target genes and molecular biological mechanisms for the modulation of CA on the spleen and gut in PD. Remarkably, CA restored some gene expressions to normal level. Our results highlighted that the neuroprotection of CA might be associated with the manipulation of CA on brain-spleen and brain-gut axes in PD.

3-Pyridinylboronic acid normalizes the effects of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine exposure in zebrafish embryos.

1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that damages dopaminergic neurons. Zebrafish has been shown to be a suitable model organism to investigate the molecular pathways in the pathogenesis of Parkinson's disease and also for potential therapeutic agent research. Boron has been shown to play an important role in the neural activity of the brain. Boronic acids are used in combinatorial approaches in drug design and discovery. The effect of 3-pyridinylboronic acid which is an important sub-class of heterocyclic boronic acids has not been evaluated in case of MPTP exposure in zebrafish embryos. Accordingly, this study was designed to investigate the effects of 3-pyridinylboronic acid on MPTP exposed zebrafish embryos focusing on the molecular pathways related to neurodegeneration and apoptosis by RT-PCR. Zebrafish embryos were exposed to MPTP (800 µM); MPTP + Low Dose 3-Pyridinylboronic acid (50 µM) (MPTP + LB) and MPTP + High Dose 3-Pyridinylboronic acid (100 µM) (MPTP + HB) in well plates for 72 hours post fertilization. Results of our study showed that MPTP induced a P53 dependent and Bax mediated apoptosis in zebrafish embryos and 3-pyridinylboronic acid restored the locomotor activity and gene expressions related to mitochondrial dysfunction and oxidative stress due to the deleterious effects of MPTP, in a dose-dependent manner.

Protective Effect of Isopulegol in Alleviating Neuroinflammation in Lipopolysaccharide-Induced BV-2 Cells and in Parkinson Disease Model Induced with MPTP.

BACKGROUND: Parkinson's disease (PD) is the most prevalent disease linked with age-associated neuronal degeneration. Phytotherapeutic compounds or agents have gained increased importance because of their increased specificity and minimal side effects. Isopulegol, a monoterpene, was utilized in the present study because of its wide range of therapeutic properties. Our aim was to examine the underlying mechanism of anti-neuroinflammatory action and neuroprotective efficacy of isopulegol in cell lines and in an experimental animal model of PD. METHODS: The MTT assay was performed in microglial BV-2 cells subjected to lipopolysaccharides (LPS). The release of NO and synthesis of ROS intracellularly in BV-2 cells were detected. C57BL/6 mice induced with MPTP were examined for motor function and coordination. Expression of proinflammatory mediators was also assessed both in vivo and in vitro. Histopathological sections of brain and expression of iNOS and COX-2 were also analyzed. RESULTS: BV-2 cells did not exhibit noticeable toxicity at selected concentrations and LPS-incubated cells showed marked elevation of NO levels and increased production of intracellular ROS. Increased expression of proinflammatory cytokines was also observed. Motor function and coordination deficits were observed in mice induced with MPTP. Histopathological abnormalities and increased iNOS and COX-2 expression were noted in MPTP-induced mice. Administration of isopulegol reversed the changes brought about by LPS and MPTP. CONCLUSION: The study indicated that isopulegol is a potential therapeutic drug against clinical complications of PD.

Protective effects of berberine against MPTP-induced dopaminergic neuron injury through promoting autophagy in mice.

Berberine, an isoquinoline alkaloid isolated from Coptis chinensis, has been widely studied for its efficacy in the treatment of neurodegenerative diseases. However, the detailed mechanisms are unknown. In this study, the effects of berberine on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice model of Parkinson's disease were investigated. We showed that treatment with berberine significantly ameliorates the degeneration of dopaminergic neurons in substantia nigra compacta (SNc) and improves motor impairment in MPTP-treated mice. Berberine also significantly decreased the level of α-synuclein and enhanced the microtubule-associated protein light chain 3 (LC3-II)-associated autophagy in the SN of MPTP-treated mice. Furthermore, adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) was activated by berberine. Berberine's actions were abolished by pre-treatment with 3-methyladenine (an autophagy inhibitor) or compound c (an AMPK inhibitor) in the MPP+-treated SH-SY5Y cells. These results suggested that the protective effects of berberine on the toxicity of MPTP could be attributed to berberine-enhanced autophagy via the AMPK dependent pathway.

Treatment of Parkinson's disease in Zebrafish model with a berberine derivative capable of crossing blood brain barrier, targeting mitochondria, and convenient for bioimaging experiments.

Berberine is a famous alkaloid extracted from Berberis plants and has been widely used as medications and functional food additives. Recent studies reveal that berberine exhibits neuroprotective activity in animal models of Parkinson's disease (PD), the second most prevalent neurodegenerative disorders all over the world. However, the actual site of anti-PD action of berberine remains largely unknown. To this end, we employed a fluorescently labeled berberine derivative BBRP to investigate the subcellular localization and blood brain barrier (BBB) permeability in a cellular model of PD and zebrafish PD model. Biological investigations revealed that BBRP retained the neuroprotective activity of berberine against PD-like symptoms in PC12 cells and zebrafish, such as protecting 6-OHDA induced cell death, relieving MPTP induced PD-like behavior and increasing dopaminergic neuron loss in zebrafish. We also found that BBRP could readily penetrate BBB and function in the brain of zebrafish suffering from PD. Subcellular localization study indicated that BBRP could rapidly and specifically accumulate in mitochondria of PC12 cells when it exerted anti-PD effect. In addition, BBRP could suppress accumulation of Pink1 protein and inhibit the overexpression of LC3 protein in 6-OHDA damaged cells. All these results suggested that the potential site of action of berberine is mitochondria in the brain under the PD condition. Therefore, the findings described herein would be useful for further development of berberine as an anti-PD drug.

N-3 PUFA-Deficiency in Early Life Exhibits Aggravated MPTP-Induced Neurotoxicity in Old Age while Supplementation with DHA/EPA-Enriched Phospholipids Exerts a Neuroprotective Effect.

INTRODUCTION: Malnutrition in early life affects the growth and development of fetus and children, which has a long-term impact on adult health. Previous studies reveal a relationship between dietary omega-3 polyunsaturated fatty acid (n-3 PUFA) content, brain development, and the prevalence of neurodevelopmental disorders and inflammation. However, it is unclear about the effect of n-3 PUFA-deficiency in early life on the development of Parkinson's disease (PD) in old age, as well as the neuroprotective effect of DHA- and EPA-enriched phospholipids (DHA/EPA-PLs) supplemented in old age in long-term n-3 PUFA-deficient mice. METHODS AND RESULTS: The PD mice induced by 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) in n-3 PUFA-adequate (N) and -deficient (DEF) group are supplemented with a DHA/EPA-PLs diet for 2 weeks (N+DPL, DEF+DPL). DHA/EPA-PLs supplementation significantly protects against MPTP-induced impairments. The DEF+DPL group shows poorer motor performance, the loss of dopaminergic neurons, mitochondrial dysfunction, and neurodevelopment delay than the N+DPL group, and still did not recover to the Control level. CONCLUSIONS: Dietary n-3 PUFA-deficiency in early life exhibits more aggravated MPTP-induced neurotoxicity in old age, than DHA/EPA-PLs supplementation recovers brain DHA levels and exerts neuroprotective effects in old age in long-term n-3 PUFA-deficient mice, which might provide a potential dietary guidance.

Caffeine, a natural methylxanthine nutraceutical, exerts dopaminergic neuroprotection.

Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects more than 10 million people worldwide. Oxidative stress and mitochondrial dysfunction play a significant role in altering the homeostasis of energy production and free radical generation. Current PD therapies are focused on reducing the cardinal symptoms rather than preventing disease progression in the patients. Adenosine A2A receptor (A2A R) antagonist (Istradephylline) combined with levodopa shows a promising therapy for PD. In animal studies, caffeine administration showed to improve motor functions and neuroprotective effect in the neurons. Caffeine is probably the most extensively used psychoactive substance. In this current study, we investigated the neuroprotective effect of caffeine against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurodegeneration. Here, we demonstrate that caffeine improves behavioral and neurotransmitter recovery against MPTP-induced toxicity. Caffeine restores endogenous antioxidant levels and suppresses neuroinflammation. Our finding suggests that the blockage of A2AR is a promising disease-modifying therapy for PD. Target engagement strategies could be more beneficial in preventing disease progression rather than symptomatic reliefs in PD patients.

Xanthotoxin reverses Parkinson's disease-like symptoms in zebrafish larvae and mice models: a comparative study.

BACKGROUND: The aim of this study is to preliminary evaluate the antiparkinsonian activity of furanocoumarin-xanthotoxin, in two behavioral animal models, zebrafish larvae treated with 6-hydroxydopamine and mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in order to compare both models. METHODS: Xanthotoxin was isolated from Pastinaca sativa L. (Apiaceae) fruits. Then, the compound was administered by immersion to zebrafish 5 days after fertilization (dpf) larvae or intraperitoneally to male Swiss mice, as a potential therapeutic agent against locomotor impairments. RESULTS: Acute xanthotoxin administration at the concentration of 7.5 µM reversed locomotor activity impairments in 5-dpf zebrafish larvae. In mice model, acute xanthotoxin administration alleviated movement impairments at the concentration of 25 mg/kg. CONCLUSIONS: The similar activity of the same substance in two different animal models indicates their compatibility and proves the potential of in vivo bioassays based on zebrafish models. Results of our study indicate that xanthotoxin may be considered as a potential lead compound in the discovery of antiparkinsonian drugs.

Protection by rhynchophylline against MPTP/MPP+-induced neurotoxicity via regulating PI3K/Akt pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Isolated from Uncaria rhynchophylla (U. rhynchophylla), rhynchophylline (Rhy) has been applied for treating diseases related to central nervous system such as Parkinson's disease. Nevertheless, the molecular mechanism of the neuroprotective effect has not been well interpreted. AIM OF THE STUDY: To investigate the effects of Rhy on MPTP/MPP + -induced neurotoxicity in C57BL/6 mice or PC12 cells and study the mechanisms involved. MATERIALS AND METHODS: The neuroprotective effect of Rhy on MPTP-induced neurotoxicity was evaluated by spontaneous motor activity test, as well as a test of rota-rod on a rat model of Parkinson's disease. The numbers of TH-positive neurons in the substantia nigra pars compacta (SNpc) was assessed by immunohistological. CCK-8, lactate dehydrogenase (LDH), reactive oxygen species (ROS), the concentration of intracellular calcium ([Ca2+]i) and flow cytometry analysis were performed to evaluate the pharmacological property of Rhy on 1-methyl-4-phenylpyridinium (MPP+) induced neurotoxicity in PC12 cells. Besides, LY294002, a PI3K inhibitor was employed to determine the underlying molecular signaling pathway revealing the effect of Rhy by western-blot analysis. RESULTS: The results showed that Rhy exhibited a protective effect against the MPTP-induced decrease in tyrosine hydroxylase (TH)-positive fibers in the substantia nigra at 30 mg/kg, demonstrated by the immunohistological and behavioral outcomes. Furthermore, it has been indicated that cell viability was improved and the MPP+-induced apoptosis was inhibited after the treatment of Rhy at 20 µM, which were severally analyzed by the CCK-8 and the Annexin V/propidium iodide staining method. In addition, Rhy treatment attenuated MPP+-induced up-regulation of LDH, ([Ca2+]i), and the levels of ROS. Besides, it can be revealed from the Western blot assay that LY294002, as a selective Phosphatidylinositol 3-Kinase (PI3K) inhibitor, effectively inhibited the Akt phosphorylation caused by Rhy, which suggested that Rhy showed its protective property through the activated the PI3K/Akt signaling pathway. Moreover, the Rhy-induced decreases of Bax and caspase-3 as the proapoptotic markers and the increase of Bcl-2 as the antiapoptotic marker, were blocked by LY294002 in the MPP+-treated PC12 cells. CONCLUSIONS: Rhy exerts a neuroprotective effect is partly mediated by activating the PI3K/Akt signaling pathway.

ß-Caryophyllene exerts protective antioxidant effects through the activation of NQO1 in the MPTP model of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder, caused by the selective death of dopaminergic neurons in the substantia nigra pars compacta. ß-caryophyllene (BCP) is a phytocannabinoid with several pharmacological properties, producing anti-inflammatory and antihypertensive effects. In addition, BCP protects dopaminergic neurons from neuronal death induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), yet it remains unclear if this effect is due to its antioxidant activity. To assess whether this is the case, the effect of BCP on the expression and activity of NAD(P)H quinone oxidoreductase (NQO1) was evaluated in mice after the administration of MPTP. Male C57BL/6 J mice were divided into four groups, the first of which received saline solution i.p. in equivalent volume and served as a control group. The second group received MPTP. The second group received MPTP hydrochloride (5 mg/kg, i.p.) daily for seven consecutive days. The third group received BCP (10 mg/kg) for seven days, administered orally and finally, the fourth group received MPTP as described above and BCP for 7 days from the fourth day of MPTP administration. The results showed that BCP inhibits oxidative stress-induced cell death of dopaminergic neurons exposed to MPTP at the same time as it enhances the expression and enzymatic activity of NQO1. Also, the BCP treatment ameliorated motor dysfunction and protected the dopaminergic cells of the SNpc from damage induced by MPTP. Hence, BCP appears to achieve at least some of its antioxidant effects by augmenting NQO1 activity, which protects cells from MPTP toxicity. Accordingly, this phytocannabinoid may represent a promising pharmacological option to safeguard dopaminergic neurons and prevent the progression of PD.

Pyridoxine induces glutathione synthesis via PKM2-mediated Nrf2 transactivation and confers neuroprotection.

Oxidative stress is a major pathogenic mechanism in Parkinson's disease (PD). As an important cellular antioxidant, glutathione (GSH) balances the production and incorporation of free radicals to protect neurons from oxidative damage. GSH level is decreased in the brains of PD patients. Hence, clarifying the molecular mechanism of GSH deficiency may help deepen our knowledge of PD pathogenesis. Here we report that the astrocytic dopamine D2 receptor (DRD2) regulates GSH synthesis via PKM2-mediated Nrf2 transactivation. In addition we find that pyridoxine can dimerize PKM2 to promote GSH biosynthesis. Further experiments show that pyridoxine supplementation increases the resistance of nigral dopaminergic neurons to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in wild-type mice as well as in astrocytic Drd2 conditional knockout mice. We conclude that dimerizing PKM2 may be a potential target for PD treatment.

Ginger and 6-shogaol protect intestinal tight junction and enteric dopaminergic neurons against 1-methyl-4-phenyl 1,2,3,6-tetrahydropyridine in mice.

Objective: Ginger and its compound, 6-shogaol, have been known for improving gastrointestinal (GI) function and reducing inflammatory responses in GI tract. Recently, the treatment of GI dysfunction has been recognized as an important part of the management of neurodegenerative diseases, especially for Parkinson's disease (PD). In this study, we investigated whether ginger and 6-shogaol attenuate disruptions induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on the intestinal barrier and the enteric dopaminergic neurons.Methods: C57BL/6J mice received MPTP (30 mg/kg) for 5 days to induce GI alterations. Ginger (30, 100, 300 mg/kg) and 6-shogaol (10 mg/kg) were treated by gavage feeding for 15 days including the period of MPTP injection.Results: Ginger and 6-shogaol protected intestinal tight junction proteins disrupted by MPTP in mouse colon. In addition, ginger and 6-shogaol suppressed the increase of inducible nitric oxide synthase, cyclooxygenase-2, TNF-α and IL-1ß activated by macrophage. Moreover, ginger and 6-shogaol suppressed the MPTP-induced enteric dopaminergic neuronal damage via increasing the cell survival signaling pathway.Conclusion: These results indicate that ginger and 6-shogaol restore the disruption of intestinal integrity and enteric dopaminergic neurons in an MPTP-injected mouse PD model by inhibiting the processes of inflammation and apoptosis, suggesting that they may attenuate the GI dysfunction in PD patients.

Role of gold nanoparticle from Cinnamomum verum against 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) induced mice model.

Parkinson's disease (PD) is a general neurodegenerative disorder which largely has an effect on the society of the aged populations. PD is distinguishedwith loss of dopaminergic (DA) neurons in the substantia nigra. The exceptional properties of gold nanoparticles (AuNPs) have fascinated great attention in biomedical applications. In this present study, we explored theprospective beneficial effects of AuNPs synthesized from Cinnamomum verum on PD. PD rat models were established through MPTP injection treatment and AuNPs was administered. Administration of AuNPs reduces effect of MPTP-induced oxidative stress and motor abnormalities observed in PD rats. In addition ELISA analysis demonstrated that AuNPs treatment significantly attenuates Tumor Necrosis Factor-α (TNF-α), Interleukin-1ß (IL-1ß) and Interleukin-6 (IL-6) expression levels. Consequently, we investigated TLR/NF-κB pathway to examine the function of AuNPs on MPTP- induced PD rats. We found that AuNPs suppressed the alterations in the pathway of TLR/NF-κB associated molecules in MPTP stimulated PD rats. Hence, our results suggest that AuNPs attenuates MPTP introduced motor disorders, oxidative stress, activated inflammatory cytokines and activated TLR/NF-κB signaling in PD rats. In conclusion, AuNPs ease PD symptoms by the inhibition of TLR/NF-κB signaling pathway and recommend promise approach in the treatment of neurodegenerative diseases such as PD.

The Ameliorative Effects of the Ethyl Acetate Extract of Salicornia europaea L. and Its Bioactive Candidate, Irilin B, on LPS-Induced Microglial Inflammation and MPTP-Intoxicated PD-Like Mouse Model.

Hyperactivation of microglia, the resident innate immune cells of the central nervous system, exacerbates various neurodegenerative disorders, including Parkinson's disease (PD). Parkinson's disease is generally characterized by a severe loss of dopaminergic neurons in the nigrostriatal pathway, with substantial neuroinflammation and motor deficits. This was experimentally replicated in animal models, using neurotoxins, i.e., LPS (lipopolysaccharides) and MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). Salicornia europaea L. (SE) has been used as a dietary supplement in Korea and Europe for several years, due to its nutritional and therapeutic value. In this study, we intend to investigate the antineuroinflammatory and anti-PD-like effects of the bioactive fraction/candidate of the SE extract. Initially, we screened various fractions of SE extract using an in vitro antioxidant assay. The optimal fraction was investigated for its in vitro antineuroinflammatory potential in LPS-stimulated BV-2 microglial cells and in vivo anti-PD-like potential in MPTP-intoxicated mice. Subsequently, to identify the potential candidate responsible for the elite therapeutic potential of the optimal fraction, we conducted antioxidant activity-guided isolation and purification; the bioactive candidate was structurally characterized using nuclear magnetic resonance spectroscopy and chromatographic techniques and further investigated for its in vitro antioxidative and antineuroinflammatory potential. The results of our study indicate that SE-EA and its bioactive candidate, Irilin B, effectively alleviate the deleterious effect of microglia-mediated neuroinflammation and promote antioxidative effects. Thus, they exhibit potential as therapeutic candidates against neuroinflammatory and oxidative stress-mediated PD-like neurodegenerative complications.